/Engine/Source/Runtime/GeometryCore/Public/DynamicMesh/DynamicMesh3.h
Utility function that returns one or two triangles of edge, used to enumerate vertex one-ring triangles The logic is a bit tricky to follow without drawing it out on paper, but this will only return each triangle once, for the 'outgoing' edge from the vertex, and each triangle only has one such edge at any vertex (including boundary triangles)
[FIndex2i](API\Runtime\GeometryCore\FIndex2i) GetOrderedOneRingEdgeTris ( int VertexID, int EdgeID ) const